In modern biological and medical imaging technologies, multiple imaging channels or multiple imaging modalities are frequently used together to offer complementary or additional information. For instance, a fluorescence channel can be used together with a white light channel to identify fluorescence signal from biological or molecular targets on top of the anatomical features presented in the white light image. As another example, a functional image of radioactive agents can be shown on a tomographic anatomical image, such as that produced by computed tomography (CT) or magnetic resonance imaging (Mill), to help localize diseases in a subject (U.S. Pat. No. 8,538,504; Yoshino et al. (2015) J. Radiation Res., 56:588-593).
Frequently, a pseudo-color or a color map is selected for one image channel so that it can better provide additional information when visualized on top of one or more other image channels. This concept has been used in many different research areas, such as those of clinical translational studies, as well as in medical care areas when applying a variety of imaging technologies.
Very often, real-time visualization is critical to enabling rapid recognition and understanding of imaging information presented in the format of a still frame, an animation, an augmented view, or a video. This can be particularly important when timely decision-making is required in response to accurate perception of a scenario via one or more imaging modalities. With this in mind, developments have been made in not only optical collection and sensing electronics for fluorescence, but in the uses of color maps and pseudo colors as applied to overlaid images (Elliot et al. (2015) Biomedical Optics Express, 6:3765-3782). In most of these scenarios, a reflective or white light image is as an underlying image that is presented together with one or more superimposed or co-localized fluorescence results (U.S. Pat. Nos. 7,330,749; 8,131,476).
In visualizing overlaid signals on a display, different perception factors, such as those of color selection, lightness, and transparency/alpha, can be adjusted. As human eyes are most sensitive to lightness, a fusion image can use a constant color map with changing lightness to indicate the most important scalar value, such as imaging agent concentration, targeted molecule concentration, grading, depth, severity, etc. Alternatively, a presentation scheme using a lookup table of different color saturations or color hues can be used to indicate scalar values. Information can also be presented by relying on differing transparency/alpha values at constant lightness and hue.
However, with these image fusion presentation schemes, it is often difficult for an operator to see the pseudo colors against the background of an underlying image. This is particularly the case when the underlying image channel is a true-color reflective light image or a bright tomographic section of a tissue or an object, as these are frequently characterized by large variations in color or brightness. For example, an underlying image can be a natural-light image of pink or light-red tissue with deeper red or blue vasculature.
To assist in visualizing signal with minimal interference, it has been proposed to allow a user to manually switch off one or more image channels, such as a reflective light channel, in order to better recognize the signal associated with another channel before turning the off channels back on. Alternatively, a component of a composite picture can be sinusoidally pulsed relative to the other elements of the composite picture (Glatz et al. (2014) J. Biomedical Optics, 19:040501). In this approach, the average background hue is calculated in order to guide the selection of the pulsed color. Yet these techniques can pose problems of decreased time efficiency, reduced ease-of-use, or lower effectiveness, particularly when presenting weak signals.